Joint for high-tension electric cables



Jan. 8, 1929. y

L. EMANUEL! JOINT FOR HIGH TENSION ELECTRIC CABLES 1925 3 Sheets-Sheet Filed Sept. 1

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File d Sept. 1, 1925 L EMANUEL] JOINT FOR HIGH TENSION ELECTRIC CABLES Jan. 8, 1929.

Jan. 8, 1929.

L. EMANUELl JOINT FOR HIGH TENSION ELECTRIC-CABLES Filed Sept. 1925 5 Sheets-Sheet attozmq reamed Jan. 8, 1929.

UNITED STATES- PATENT OFFICE.

LUIGI EMANUELI, OF MILAN, ITALY, ASSIGNOR T0 SOCIETA- ITALIANA PIRELLI, OF N MILAN, ITALY, ACORPQRATION OF ITALY.

. JOINT FOR HIGH-TENSION ELECTRIC CABLES.

Application filed September 1, 1925, Serial No. 53,929, and in Italy Italy 11, 1925.

The present invention relates to electric cables which aredesigned to carry very high voltage currents and which are located in underground conduits. Briefly the cable comprises a stranded conductor which surrounds a hollow core and is in turn sur-.

rounded by suitable insulating material, such as paper, and a metallic lead sheath. The hollow core isv filled with a relatively thin oil which impregnates the paper and acts as an insulating medium. Thesupply of oil is maintained under pressure in the cable by reservoirs located at suitable points which have special arrangements to keep air out of the cable and also the oil. When the cable is of considerable length, it must be divided into several sections so as to avoid too great a drop of pressure as the oil' flows through the core, or too great a head for the oil. At the points where the cable sections are joined, it is necessary to provide special means first to establish the electrical connection and second, to separate the oil supply of one section from another.

The object of my invention is to provide an improved joint for high tension cables of the above-mentioned type which will effectively unite the sections electrically and will prevent the oil in the cable from flowing from one section to another, and in which the conductor will be effectively in sulated from the ground.

In the accompanying drawings, which are illustrative of my invention: Figure 1 is a longitudinal section of a joint where the conductors are in axial alinement; Fig. 2 is a vertical section of ajoint where the conductors are inclined at an angle to each other;.Fig. 3 is an enlarged sectional View of the upper portion of the joint shown in Fig. 2; Fig. 4 is a similar view of the lower portion of the joint; and Figs. 5 and 6 are detail views of parts of the joint.

Referring to Fig. 1, 7 indicates the end of one section of a cable or conductor'and 8 the end of an adjacent section. The paper or other factory-made insulation 9 is removed from the ends of the conductors, after which they are inserted in sockets formed in metal blocks 1Q. The two blocks are to a minimum. Between the tubes and the insulation and the conductors is a cylindrical space or chamber 13 which is filled with some relatively insulating properties. Surrounding the parts is a casing 14:, usually made of brass, the two parts of which are soldered together; the casing being reduced in diameter at its ends so as to fit thetubes and hold them central with respect to the conductors. To each of said reduced endsis' attached a thimble 15, the outer end 'of which is secured to the lead sheath 16 of the cable as by a wiped joint. Prior to assembling the casng in place the parts are carefully taped as indicated at 16, care being exercised to have the tape tightly wound over the parts and to prevent any moisture from the hands of the jointer or otherwise from getting-between the layers of tape. The spaces 13 between the tubes 12 and the insulation, and

within the thimbles 15 and the conductors,

are filled with thin oil which may be supplied directly from the core of the con-v ductors or from suitable reservoirs through inlets such as 17 for example.

In Fig. 2 is shown an arrangement where the conductors are inclined to each other. In this case, a cast iron box 18 is prpvided within which is a thin-walled lead casing 19 comprising a base portion and a cover, said portions being united by a wipedjoint 20. The box is provided with a removable bronze cover 21, upon which the conductors alilid their connecting parts are supported; t e of dissimilar metals being to reduce eddy light oil having good purpose of making the box and cover current losses. The cover portion of the inner lead casing'19 is also supported by the box cover 21 so that'it and the other parts i can be removed from the box as a unit. The

, various partsof the joint, prior to sealing of the inner casing, are carefully taped as described in connection with Fig. 1, the outline of the tape being indicated by dotted- I lines.

- Inent with respect to the other, thus prevent- .ing any strain on the insulating tubes 12,

which mightcause them to crack. Referringinow to Figs. 3 and 4, which illustrate details not shown in the previous figures, 16 indicates the lead sheath and'9 the factory-wound insulation, which is paper... I

addition, each bar 36' is pressed outwardly In the cover 21 of the box is a socket 22in which is mounted asleeve 23 that is soldered thereto, the upper end of the sleeve being flared outwardly. Inside this sleeve fits-the lower portion of the thimble 15, which lat- 'ter is'fiared outwardly at its upper end and is connected to the lead sheath'by joint 24, the joint betweenthe sleeve and thimble bein similarly formed.

' .The lead sheath having been cut away to expose the factory insulation 9, a tightlywound paper tube 25 havin abeveled upper end is slipped over it. gurrounding the sald tube end, the factory insulation'and the lower endof the sheath is a metal funnel 26, Fig. 6, made in two parts having coma I the pose of the funnel being to diminish complished by the construction shown in Fig."

1., panlon cars 27 .to receive clampin screws,

the longitudinal-electrical stresses at this polnt. The porcelain or other insulating tube 12 hasits ends fitted in recesses orsockets; the upper end in a socket 22' on the underside of thebox cover21 and the. lower ,series of grooves, parallel or otherwise,'and.

theo dth" b't thg Se gm Ves an 6 Space 3 we??? 8 result that" the diameter of he circle defined 1 by the'bars is less than: the diameter ofsaid.

parts, are filed with cement 28.

In a, construction of this charac'ter,.it is necessary to establish good electrical connection etween the high tension cable and the connecting block or member 10. It is also necessary to have a connection of such character that the conductor can be readily inserted and removed at will, This is ac- 4, in which the conductor comprises a central metal core 30 made after the fashion of'a' coiled spring and surrounded bythestrands 31 of the conductor which are made ofrelatively small wires and outside of which-is thefactory insulation. Inside the conductor and engaging the core is a copper tube 32 which composed of thin strips of conducting material such as copper, and they also act as a wiped is soldered to the strands 31 the purposebeing to support the strands from the inside. holdthe end of the core in place and also aifordi'for the oil which is contained in the cable a freefpassage to and from the cham here that surround the various parts of the In preparing the connection, the insulation is removed from the end of the conductor, and. over it is slipped a relatively-longsleeve or tube 33 whichis' soldered to the wires or strands 31. The tube has a shoulder 34 at'the top and a smaller shoulder 35 at the bottom; and between these shoulders is v a plurality of radially-movable 'contact bars 36 each connected to the upper shoulder 34 A by anelastic connector 37 which carries the current. As shown, the connectors 37 are sprin s to force the bars outwardly; and in by one or more leaf springs'38.

In order to facilitate the introduction of' the spring-pressed contact bars 36 into the inner or lower socket 39 formed in the connecting block: or member 10, it is necessary to rovide. a means to restrain said bars against the action of the spring connectors Figs, 4 and 5 and-comprising an upper flat ring 40, a lower ring- 41 and vertical elements 42 which are situatedbetween the contact bars 36, as best shown inFig. 4; the 1 Vertical elements 42 being rigidly connected to therings 40 and 41. When in the position shown in Fig. 4, the ring 41 holds the lower ends ofthe contact bars against the action of the springs, but when the partsarerelatively displaced in axial direction the ring moves into the. notches 43 in said bars, {hereby releasing the springs, as will appear ater. 1'. v

' Prior to inserting the cable end into the 1 socket 39,\the cageiszso' adjusted that the rings 40 and 41 hold the contact bars 36 at i the top and bottom, the springs being under reater than normal compression with the space between the shoulders 34 and 35 of the sleev'e'33 is made; slightly greater than the length of the cage. so that when the cable end is pressed downward, it pushes down the 1 sleeve and with it the cage untilitheupper the socket 39; and to accomplish this, the

ring 40' engages the upper end of the socket whereupon the movement of the cage ,is arrested. Then as themov ement ofthe sleeve and-bars continues, the latter finally, dis -v 1 engage said ring and move outwardly due to the springs. The same action causes the .loWer ring 41 to .move into the notches 43,

whereupon the bars 36 will be pressed into contact with the wall of the socket throughout their length. In removing the cable end, it is onlynecessary .to pull it out, the

contact bars sliding on the wall of the socket.

To replace the cable end, the cage is adjusted to again confine the bars as previously described.

The casings are filled with oil under suitable pressure, as are'also the chambers or spaces between the insulating tubes and the various parts of the joint. This oil may be supplied from the center passage in the conductor, which is itself supplied from a reservoir, to the interior of the joint. In any oil one section might event, the oilwhich is contained in one cable section is prevented from flowing into the other.- This is important because one cable section may be higher than the other, and without some means for stopping the flow of drain another section, thereby causing a breakdownof the insulation.

It is to be noted that the oil which is contained in each of the cable sections is sealed therein and cannot flow or escape from one to the other.

This is true not only of the mainbody of oil within the core but also of that within the dielectric material. It is quite apparent that themain bodies of oil in two adjacent conductors must be separated,

for the cores are large and one might easily drain the other, especially in the event of a rupture of a sheath. It is not so apparent,

but it is nevertheless true, that the oil in the dielectric of one section must be separated from that in the other, since otherwise there would be seepage and this constant seepage could, with the cable sections at different ele-.

. rations, result in building up such a hydrostatic head in the .lower section as to causeor leakage at the varirupture of the sheath one joints,thereby resulting in injury to one and probably to hence has free'access the both sections.

jury to a cable means that it has of'service-and replaced, all of which means loss of time and the expenditure of a substantial'sum of moneyand more or less protracted interference with the supply of cur- Any such inrent to customers unless supplementary conductors are immediately available. Oil uner' pressure is maintained in the core 30 and. to all the spaces in and about the cable end. It cannot escape from the tube 12 due tdthe. cement fillings 28 at its. ends. Nor can it escape at any point above orbeyond the tube due to the thimble -15 and associated parts which are secured fluid-tight to each other, or from the closed socket 22 at the lower or other end. I

I claim as my invention 1. In a high tension electric cable system,

wholly or partially to be cut out 1 the combination, with a pair of cable sections to be jointed; of a pair of conducting blocks each formed with-an inner socket to receive the bare end of a cable section and with an outer socket concentric with the inner one; a tube of insulating material fitted over the end of each cable section and having its own end mounted in the outer socket in the corresponding block; and a flexible conductor con each formed with an inner socket to receive the bare end of a cable section and with an outer socket concentricwith the inner one; a tube of insulating material fitted over the endfof each cable section and having its own end mounted in the outer socket inthe corresponding block; a flexible conductor connecting said blocks to enable relative mov ement therebetween; a wrapping of insulating tape wound around both blocks and their connected insulating tubes; and a casing enclosing the parts so wrapped.

4. In a high'tension'electric' cable system, the -combination,.with a pair of cable sections to be jointed; of a pair of connected conducting blocks, one for each cable section, each block provided with a socket; a set of movable conductor bars connected with. the

bare end of each cable section and adapted to be inserted with. the same into the socket in the respective block; and means associated with said bars for yieldingly forcing them radially outward into contact with the socket walls.

5. In a high tension-electric cable system, the combination, with a pair of cable sections to be jointed; of a pair of connected conducting} blocks, one for each cable section, each block provided with a socket; a set of movable conductor bars connected with the bare end of each cablesection and adapted to be inserted with the same into the socket in the respective block; restraining means associated with said bars for releasably holding them in retracted positioifto enable their insertion into the sockets; and means for forcing the bars radially outward into contact with the socket'walls when released from the action of said restraining means.

6. In a high tension electric cable system, the-combination, with a pair of cable secjtions to be jointed; of a pair of connected conducting blocks, one-for each cable section,

each block provided with a socket; a'set of movabl conductor bars connected with the bare end of each cable section and adapted to be inserted with the same into the socket v cage.

i with said bars to hold them in retracted posiin the respective block a cage fitting around each set of bars to releasably hold them in retracted position and thereby enable their insertion into the corresponding socket; and means for yieldingly forcing the bars radially outward into contact with the'soc'ketwalls when"released from the action of the 7. In a high tension electric cable system, the combination, with a pair of cable sections vto be jointed; of a pair of connected con- -duct1ng blocks, one for each cable section;

each block provided with a socket; a set 0 movable conductor bars connected with the bare end of each cable section and adapted to be inserted with the same into the socket in the respective block; a cage fitting around each set of bars and embodying at least one annular member which is releasably engaged tion and thereby enable their insertion into the corresponding socket; and means for yieldinglyforcing said bars radially outward into contact with the socket walls when discharged from such member.

' 8. In a high tension electric cable'system, the combination, with a pair of cable sections to be jointed; of a pair of connected conducting blocks, one for each cable section,

' e s d the combination, with a pair of cable sec tions to be-jointed; of a pair of connected conducting blocks, one for each cable section, each block provided with a socket; a set of movable conductor bars connected with the bare end of each cable section and adapted to be inserted with thesame into the socket from such member.

inthe respective block, each set of bars being notched; a cage fitting around each set of bars and embodying an annular member which is releasably engaged in the notches in the bars. to hold the latter in retracted position and thereby enable their insertion into the respective socket; and means for yieldingly forcing said bars radially outward into cone tact-with the socket walls when disengaged 10. A high tension electric cable system, according to claim 6-, in which the cage embodies upper andlower rings and a: series 1 l j of vertical elements connecting the rings and spaced from one another to fit between adjacent bars.

11. high tension electric'cable system, accordingto claim 6, in which the cage embodies upper and lower rings and a series of vertical element's connecting the rings and spaced from one another to fit between ,i ad acent bars; and in which one of the rings is adapted for releasable engagement in notches formed in the *bars.

'12. In a high tension'electric cable system,

the combination, with a pair of cable sections to be jointed; of a pair of connected conducting blocks, onefor each cable section, each block provided with a socket; a conducting tube secured to the bare end of each cable section and havingspace'd upper and lower circumferential shoulders; a set of movable conductor bars carried by each tube between the shoulders, thereon and adapted to be inserted with the tube and c'able end into the socket in the respective block; a

cage fitting loosely over each set of bars between the shoulders on the corresponding tube to releasably hold said bars in retracted position and thereby enable their insertion into the corresponding socket; and means for yieldingly forcing the bars radially outward into contact with the socket walls when released "from the action of the cage.

13. In a high tension electric cable system,

the combination, with a pair of cable sections to be jointed; of a pair of connected conducting blocks, one for each cable section,

each block provided with a socket; and v an expansible and contractible set of condhctor bars connected with the bare end of each cable section for releasable insertion with the same into the socket in'the respcctive block; v

14;. In a high tension electric cable system, the combination, with a pair of c'able sections to be jointed; of a pair of connected conducting blocks,

tion, provided WIth sockets to releasably receive the bare lower-ends of the cable sections and rent from one section to the other; a case wherein said blocks are contained; a cover for said case having a pair of sockets through which the cable. sections PI'OjGCt; and a centering sleeve fitting over and jointed to the projecting portion of each cable section, said sleeves being mounted in the sockets in said cover.

15. In a high tension electric .cable system, the combination, with a 'pair of cableusec one for each cable sec thereby enable the passage of curtions to be jointed; of ax pair of connected conducting blocks each formed with an'inner socket to receive the -rbare end of a cable section and with an outer socket concentric ing its-lower end mountedin the outer socket with the inner one; aninsulating tubefitting overthe end of each cable section and havin the corresponding block; a case wherein said blocks and tubes are contained; a cover for saidcase provided upon its under face with a pair'of sockets to receive the upper ends of said tubes, and upon its upper face with a pair of sockets concentric with the under sockets'and through which the cable sections extend; and a sleeve fitting over and j ointed to the Cproj ecting portion of each cable section, sai sleeves being mounted in the outer cover sockets.

. section to the other.

17 In a high tension electric cable system, the combination, with a pair of sheathed hollow cable sections,each of which is filled with oil; of, metallic members with which the conductor ends are connected; a connector for uniting the members electrically; a casing which encloses said parts and also the adjacent ends of the cable sections and is connectedfluid-tight to their sheaths;

and tubular members within the casing, each of which surrounds one end of a cable section, is seated fluid-tight at one end and is in communication with a cable sheath at the other end, said tubular members preventing the flow of oil from one cable section to the other. e I

18. In an oil stop-joint for oil-filled sheathed cables of the character described,

the combination of a pair of metallic members which are electrically connected to the conductors; a -connector for carrying current between the members; an enclosing casing which is sealed to the sheaths of the adjacent cable sections; and hollow insulators which surround the conductor ends and are spaced from the conductors to form oil chambers, each of which chambers establishes free communication between the oil passage within a cable section and the outer surface'of the conductor insulation, said insulators each being seated fluid-tight on one of the members at, one end'and making a I fluid-tight connection with the casing at the other end; v i

19.' In a high tension cable system, the combination, with a pair of sheathed cable sections, each of which contains conductor means covered with dielectric material'and a body of fluid insulation; of a connector for electrically uniting the conductor means of adjacent sections; a casing which encloses v the connector and also the adjacent ends of the sheaths, to which latter it is sealedfluidtight; and a separate insulating enclosure for the connector end of each conductor means, which enclosure is located within the casing and is in free communication with the interlor of the sheath of said means, contains fluid insulation, and prevents the direct flow of fluid as well as the seepage of fluid through the dielectric of one cable section into the adjacent and electrically connected cable section. I

20. A high tension cable system, comprisinga pair of sheathed cable sections, each of which contains -conductor means, a fluid passage, dielectric/material and a bo dy of fluid insulation; in combination with a metal socket in electrical contact with each conductor means; a connector for carrying current from one socket to the other; an insulator for each conductor end which surrounds the same and is seated fluid-tight in a socket;

and fluid-tight means for connecting the opposite end of the insulator to the. interior of the sheath-whereby fluid is prevented from escaping from the cable section either by seepage or otherwise.

21. A sectionalized cable system, each sec-, tion comprising a high tension oil-filled hollow conductor, a dielectric covering therefor and a sheath; in combination with metallic members for electrically uniting the conductors; tubular insulators which enclose the adjacent end portions of the conductors and are sealed against the escape of oil from, the

passage within the conductor and also from i the dielectric covering, the interior of each of said insulators being in free communication with the interior of the sheath of its cable section; and a casing for the connected ends oftheconductors which is sealed to the sheaths thereof.

22. In a high tension cable system comprising a pair of hollow insulated conductors, each of which is filled with oil; a sheath for each conductor;'-connector means for ,electrically uniting the conductors; insulating tubes which loosely surround the conductor ends, are concentric therewith and are seated fluid-tight at one end of said connector means, the interior of said tubes being in free communication with the interior of their respective conductors and the insulation thereon; fluid-tight means for connecting the outer end of each tube with the interior of its associated sheath; and an enclosing casing for the connector means and tubes which is sealed to the sheaths of both conductors.

23. In an insulating joint for sheathed oil-filled cables, the combination of insulating sleeved 'oil stops respectively adapted to outside said sleeved oil stops, and means'to insulate the saidterminal connecting means comprising an-oil-filled encasement disposed v tight joints the respective ends of said insulating shell to the sheath and to the conthereabout and connected by oil-tight joints 5 at its ends to the outer ends of said insulating'sleved oil stops.

24. In an insuiating joint, the combine,-

tion of sheathed oil-filled cables, an oil stop 7 comprising an insulating shell adapted f0 enclose with clearancesa sheath stripped cable end, and means for connecting by oilductor of said cable.

In testimony whereofI aifix my signature. L

LUIGI EMANUELI. 

